\begin{tikzpicture}
    \tkzDefPoints{0/0/O}
    \tkzDefPoint(70:3.5){A}
    \tkzDefPoint(0:3.5){B}
    \tkzDefPoint(35:4.5){C}
    \tkzDefPointOnLine[pos=.55](O,C)  \tkzGetPoint{D}
    \tkzDefLine[altitude](A,D,O)  \tkzGetPoint{E}

    \tkzDrawCircle[thick](D,E)
    \tkzDrawPoint(D)
    \tkzDrawSegments(O,A  O,B  O,C)
    \tkzLabelPoints[below](O)
    \tkzLabelPoints[left](A)
    \tkzLabelPoints[below](B)
    \tkzLabelPoints[below](C)
    \tkzLabelPoints[above left](D)
    \tkzLabelPoints[left](E)
\end{tikzpicture}

